Webhooks are HTTP callbacks that receive notification messages for events. To create a webhook in PayPal, merchants configure a webhook listener and subscribe it to events. A webhook listener is a server that listens at a specific URL for incoming HTTP POST notification messages that are triggered when events occur. PayPal signs each notification message that it delivers to your webhook listener.

The IPN message service automatically notifies merchants of events related to PayPal transactions. Merchants can use it to automate back-office and administrative functions, including automatically fulfilling orders and providing customers with order status.

The PDT notification service sends transaction-related information immediately to merchants who use PayPal payment buttons. Merchants can display these transaction details on their websites to confirm that the buyer's payment was successful. Merchants can also use this information to automatically fulfill orders for digital goods.